Now, let's re-write that thinking in terms of a major chord and
alterations:

root, b9, #9, 3, b5, 5, 13, b7

Now, this scale has a two very cool properties: the first is that every note in the scale is a legitimate chord tone or alteration of a dominant chord. The second is that the scale is symmetrical in
minor thirds - that is if you take and scale note and go up or down a minor third, you'll find another scale note.

SO here's the first exciting thing: ANY chord derived from that diminished scale is a potential substitution for an altered dominant chord. That right there is worth the price of admission. For
example, the following chords are hiding in there:

So that's a whole bunch of possible chord substitutions. Since they have a b3 (well, think #9) and no 7. But here's the beauty: they're all moveable in 3rds because of the symmetry in the scale. Take
any one of those beasts, play it in place of an V chord going to I, and start sliding it up or down in thirds. With MOST of them (dim7 being the obvious counter example) you'll hit every note in the
scale eventually, thereby getting the 3 and 7 to define the chord. And you'll sound damn cool doing it because there literally is not a bad note in sight

The obvious application here is the V in a ii-V-I, but any place where an altered dominant chord appears this is fair game.